Much progress made! Three modules are now fully complete and wired up. More pots arrived, enabling completion of the Kareishuu VCOs.

The Kareishuu VCO main boards have two holes for mounting, if not using the Eurorack panel. I wired directly from the connector holes, which are conveniently labelled. It’s a lot of wire measuring, cutting, stripping and tinning. After that it goes pretty quickly.

NLC Stochaos

This module generates gates and control voltages based on pink noise or chaos or pink noise vs chaos.

Stochaos takes a clock to get it moving. A reset input is optional. It contains two random voltage generators, one noisy (stochastic) and one chaotic oscillator. There are eight pulse outputs and three stepped voltage outputs. (I left off one pulse output and one stepped output, due to panel space limitations.) On each positive clock transition the eight pulse outputs acquire a new random state, high or low. Each of the three voltage outputs step to a new value.

It’s a pink noise. The overall amplitude is adjusted by a fixed resistor. I have it at around +/-3V. The amplitude isn’t critical for internal use.

Stepped outputs #1 and #2 stay in the positive region.

Stochaos build and panel wiring

Notice the two big resistors? I missed that value when ordering parts. So I used a 1/4 watt. Luckily there was room.

The panel PCB has components for driving the outputs and LEDs.

For my project, the panel PCB faces downward. It mounts to my bracket with nylon standoffs and serves as the wiring platform.

Wires are measured and first soldered to the panel PCB. Then with the PCB mounted the wires are soldered to the panel parts.

I use 5mm standard size LEDs, super bright and water clear. The driving resistors are 4.7K. The LEDs snap into Fresnel lenses pressed in from the front. This method prevents the LED from being accidentally pushed back through the panel by an errant finger. I simply lay solder the wires to the LED leads, covering one with a small heat shrink, and the whole thing with a bigger heat shrink.

The main PCB can be removed for easy maintenance without disturbing the wiring.

The Obligatory Demo!

A big feature of the Kareishuu VCO is its linear FM capability. Two modulation signals are mixed and passed to an internal VCA for dynamic FM. One of the modulating signals is the VCO’s own sine wave and the other is any external signal. Both of these have attenuator pots. The VCA itself has an initial Gain pot and a CV input with attenuator. The FM signal is AC-coupled, but with a large capacitor that can pass LFO signals.

For this patch I sent the sine wave of one VCO to the external FM input of the other. I patched one of the positive stepped outputs of Stochaos into the VCA CV input. In the demo video I played around with the linear FM. The FM’ed sine wave appears on the scope (in yellow), with the stepped output from Stochaos on the blue channel. Stochaos was clocked by the VCO being modulated. First there is just the sine wave, then simple linear FM with the other sine wave (even going into LFO territory). I play a bit with the self-modulation, and with controlling the FM level by Stochaos.